Data errors on HP Mydrive NAS

I have a strange issue with a HP Mydrive "World edition" connected to
ethernet.
Files copied to this drive sometimes get corrupted, in a very specific
pattern.

We cannot reproduce this corruption with smaller files, less than 2 MB, but
with
files 20 MB it occurs in 80% of copies.
I copy the files by drag & drop from Explorer, or by copy / v command,
results are same. More over, copy /v does not find any error.
Then I run fc /b copy original and it finds differences.
In a ~ 20 MB file, there are few bytes (1 to 6) with one bit (same in all
cases) stuck in "1".

The drive sits in a conditioned server closet.

What can cause this? Should I look for electrical interference, magnetic
field and so on?

Can you recommend a good disk test for revealing data corruptions?

Regards,
-- pa

"Pavel A." wrote in
:

I have a strange issue with a HP Mydrive "World edition" connected
to ethernet.
Files copied to this drive sometimes get corrupted, in a very
specific pattern.

We cannot reproduce this corruption with smaller files, less than
2 MB, but with
files 20 MB it occurs in 80% of copies.
I copy the files by drag & drop from Explorer, or by copy / v
command, results are same. More over, copy /v does not find any
error. Then I run fc /b copy original and it finds
differences. In a ~ 20 MB file, there are few bytes (1 to 6)
with one bit (same in all cases) stuck in "1".

The drive sits in a conditioned server closet.

What can cause this? Should I look for electrical interference,
magnetic field and so on?

Can you recommend a good disk test for revealing data corruptions?

Regards,
-- pa

Ethernet is a serial medium that is well checksumed, so it is unlikely
that the network is causing this problem. My bet would be a loose
data bit connection somewhere between the NIC and the hard drive inside
the NAS. It sounds like you need to replace your NAS.

HTH,
John

John Wunderlich wrote:
"Pavel A." wrote in
:

I have a strange issue with a HP Mydrive "World edition" connected
to ethernet.
Files copied to this drive sometimes get corrupted, in a very
specific pattern.

We cannot reproduce this corruption with smaller files, less than
2 MB, but with
files 20 MB it occurs in 80% of copies.
I copy the files by drag & drop from Explorer, or by copy / v
command, results are same. More over, copy /v does not find any
error. Then I run fc /b copy original and it finds
differences. In a ~ 20 MB file, there are few bytes (1 to 6)
with one bit (same in all cases) stuck in "1".

The drive sits in a conditioned server closet.

What can cause this? Should I look for electrical interference,
magnetic field and so on?

Can you recommend a good disk test for revealing data corruptions?

Regards,
-- pa

Ethernet is a serial medium that is well checksumed, so it is unlikely
that the network is causing this problem. My bet would be a loose
data bit connection somewhere between the NIC and the hard drive inside
the NAS. It sounds like you need to replace your NAS.

HTH,
John


It could be RAM somewhere in the path to the platters. Say, the cache
RAM on the hard drive inside the NAS itself could be bad. Perhaps a
hard drive diagnostic, and slaving the drive to an existing computer,
would make it possible to test for that. The NAS itself may be a
small computer, with its own RAM, which would give another place
for problems to occur. Robust designs would do self-test at
startup and not start if a problem was detected. Or, to give better
run-time protection, having ECC on RAM would help detect things
such as stuck bits in any RAM being used.

Paul

Thanks. This kind of confirms my thoughts. The errors occurs on the path
from RAM (cache) to the disk drive, otherwise copy /v would fail earlier.
But OTOH, we consumers like our CE stuff to be dirt cheap... so we get what
we paid for.
--pa


"Paul" wrote in message
...
John Wunderlich wrote:
"Pavel A." wrote in
:
I have a strange issue with a HP Mydrive "World edition" connected
to ethernet.
Files copied to this drive sometimes get corrupted, in a very
specific pattern.

We cannot reproduce this corruption with smaller files, less than
2 MB, but with
files 20 MB it occurs in 80% of copies.
I copy the files by drag & drop from Explorer, or by copy / v
command, results are same. More over, copy /v does not find any
error. Then I run fc /b copy original and it finds
differences. In a ~ 20 MB file, there are few bytes (1 to 6) with one
bit (same in all cases) stuck in "1".

The drive sits in a conditioned server closet.

What can cause this? Should I look for electrical interference,
magnetic field and so on?

Can you recommend a good disk test for revealing data corruptions?

Regards,
-- pa

Ethernet is a serial medium that is well checksumed, so it is unlikely
that the network is causing this problem. My bet would be a loose data
bit connection somewhere between the NIC and the hard drive inside the
NAS. It sounds like you need to replace your NAS.

HTH,
John


It could be RAM somewhere in the path to the platters. Say, the cache
RAM on the hard drive inside the NAS itself could be bad. Perhaps a
hard drive diagnostic, and slaving the drive to an existing computer,
would make it possible to test for that. The NAS itself may be a
small computer, with its own RAM, which would give another place
for problems to occur. Robust designs would do self-test at
startup and not start if a problem was detected. Or, to give better
run-time protection, having ECC on RAM would help detect things
such as stuck bits in any RAM being used.

Paul